Some stars from Die Hard engaged in speculation, after retiring (8)

I believe the answer is:

cepheids

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'speculation after retiring' is the definition.
I know nothing about this answer so I cannot tell whether this works.

'some stars from die hard engaged in' is the wordplay.
'some stars' becomes 'ceps' (I can't explain this - if you can you should believe this answer much more).
'from' indicates anagramming the letters (from the letters).
'hard' becomes 'h'.
'engaged in' indicates putting letters inside.
'die'+'h'='dieh'
'dieh' anagrammed gives 'heid'.
'ceps' placed around 'heid' is 'CEPHEIDS'.

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I've seen this clue in The Independent.

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